#include <iostream>
#include <algorithm>
#include <vector>
#include <random>
#include <unordered_map>
using namespace std;

const int64_t p = 2000000000000000303;
vector<int64_t> ts, tsum;

std::random_device rnd;
std::mt19937 mt(rnd());
std::normal_distribution<> norm(2, p);

int N, Q;
unordered_map<int64_t, int> answer;

void init_hash() {
  ts.resize(N + 1); tsum.resize(N + 1);
  ts[0] = 1; tsum[0] = 0;
  for(int i = 0; i < N; i++) {
    ts[i] = norm(mt);
    while(__gcd(ts[i], p) != 1) {
      ts[i] = norm(mt);
    }
    tsum[i + 1] = (tsum[i] + ts[i]) % p;
  }
}

int main() {
  cin >> N >> Q;
  init_hash();
  int64_t cur_hash = 0;
  answer[cur_hash] = 0;
  for(int i = 0; i < Q; i++) {
    string c1;
    cin >> c1;
    if(c1 == "!"){
      int L, R, K;
      cin >> L >> R >> K;
      __int128_t tmp = tsum[R] - tsum[L];
      tmp = tmp * K % p;
      if(tmp < 0) tmp += p;
      cur_hash = (cur_hash + tmp) % p;
      if(answer.count(cur_hash) == 0) {
        answer[cur_hash] = i + 1;
      }
    } else {
      cout << answer[cur_hash] << endl;
    }
  }
}